The invention has particular, though not exclusive, application to switched reluctance motors. Such motors generally comprise stator and rotor pole assemblies formed of laminated sheets of magnetic material, typically motor iron. For purposes of this specification, the term "magnetic material" should be understood as a material appropriate for conduction of the magnetic fluxes necessary for motor or generator operation.
Switched reluctance motors are constructed in a variety of configurations. A stator pole assembly may have several poles integrally formed with a yoke that serves to complete magnetic paths between the poles as well as providing structural support. Often the stator will be formed of several separate and distinct stator pole assemblies; that is, the stator has a multi-unit construction. Alternatively, the stator may have a single annular yoke to which all stator poles are attached. The rotor may have a central hub with rotor poles extending radially away from the hub. Alternatively, the rotor poles may be bars of magnetic material effectively embedded or fastened within a rotating support structure. The rotor and stator poles may be equal in number, but differences in number and consequently pitch are more common to permit self-starting of the motor.
Regardless of configuration, the rotor and stator pole assemblies will have a laminated construction to reduce eddy currents. The laminations are often made by stamping plates of magnetic material in an appropriate shape. The stamping process may require separate treatment for rotor and stator pole assemblies, the complexity of the operation being dependent in part on motor design. Complex progressive stamping may be required, and those skilled in the art will appreciate the very significant cost involved in providing appropriate stamping equipment.
Those skilled in the art will appreciate that there is little distinction in the general construction or configuration of motors and generators. The latter generally comprise stator and rotor laminations. The teachings of this specification, although focussed primarily on motors, should be understood as having application to the construction of both motors and generators (including alternators).